# Apply Global Fatigue Solution Settings

Apply fatigue solution settings to the entire assembly.

Global default fatigue solution settings are applied automatically when the project is opened, but some adjustments can be made if needed.

1. In the main toolbar, click Settings > Default fatigue solution settings.
2. Under the General tab in the dialog, choose from the following options:
Option Procedure
Fatigue Method The following methods are available:
• Uniaxial
• Multiaxial
SN Model Settings
Stress Combination
The following stress combination models are available only under uniaxial fatigue method:
• Critical plane
• Absolute max principal
• Maximum principal
• Signed von Mises
• Signed max shear
Tension Damage Model
The following tension damage models are available:
• Goodman
• FKM - mean stress sensitivity input is required
Shear Damage Model
The Findley model is available for shear damage model under multiaxial fatigue method only. Findley constant and shear fatigue strength coefficient are required.
EN Model Settings
Stress Combination
The following stress combinations are available only under uniaxial fatigue method:
• Critical plane
• Absolute max principal
• Maximum principal
• Signed von Mises
• Signed max shear
Tension Damage Model
The following tension damage models are available:
• Smith, Watson, and Topper
• Morrow
Shear Damage Model
The following shear damage models are available only under multiaxial fatigue method:
• Fatemi-Socie
• Brown-Miller
Endurance limit modifying factors
1. Select Surface condition.

The following options are available: polish, ground, machine, hotroll, forge.

2. Select surface treatment.

The following options are available: Nitrided, shotpeen, coldroll.

3. Select fatigue strength reduction factor.
Number of planes Enter the number of critical planes.
3. Under the Spot weld tab in the dialog, choose from the following options:
Option Procedure
Model method The following methods are available:
• Rupp
• Modified Rupp
Mean stress correction FKM model is available.

Mean stress sensitivity input is required.

Thickness correction Thickness effect consideration.

Thickness reference and thickness reference exponent inputs are required.

TREF is used to define the reference thickness for thickness effect consideration. If the thickness of a shell (T) is greater than the specified value (TREF), the thickness effect is included by increasing the stress ( ${\sigma }_{ij}$ ) when thickness correction is applied: (1)
${\sigma }_{\mathit{ij}}={\sigma }_{\mathit{ij}}{\left(\frac{T}{\mathit{TREF}}\right)}^{\mathit{TREF}_N}$

Default thickness reference = 25mm

Default reference exponent = 0.2

Endurance limit modifying factors Certainty of survival.

Enter a value based on the scatter of the SN curve.

Default = 0.5

Number of angles Specify the number of angles to examine on sheet and nugget.

Default = 20

4. Under the Seam weld tab in the dialog, choose from the following options:
Option Procedure
Model method Volvo fatigue analysis method is available.

This method calculates the bending and membrane stresses by using stress linearization approach at specific data points at the weld toe.

The number of data points are determined by the weld length. Damage is linearly interpolated between these points.

Stress combination The following options are available:
• Normal
• Critical plane
• Absolute max principle
Mean stress correction FKM model is available.

Mean stress sensitivity input is required.

Bending ratio threshold Specify the threshold for bending ratio.

If the calculated bending ratio is higher than the threshold, an SN curve that is interpolated between membrane stress-life SN curve and bending stress-life SN curve is used. Seam weld membrane stress-life SN curve is used if the calculated value is lower than the threshold.

Default = 0.5

Maximum weld depth Specify the maximum weld depth.

The specified value sets the maximum depth for which stress linearization through the thickness of the connected part from the weld toe is performed.

Default = 5mm

Thickness correction Thickness effect consideration.

Thickness reference and thickness reference exponent inputs are required.

TREF is used to define the reference thickness for thickness effect consideration. If the thickness of a shell (T) is greater than the specified value (TREF), the thickness effect is included by increasing the stress ( ${\sigma }_{ij}$ ) when thickness correction is applied: (2)
${\sigma }_{\mathit{ij}}={\sigma }_{\mathit{ij}}{\left(\frac{T}{\mathit{TREF}}\right)}^{\mathit{TREF}_N}$

Default thickness reference = 25mm

Default reference exponent = 0.2

Endurance limit modifying factors Certainty of survival.

Enter a value based on the scatter of the SN curve.

Default = 0.5

5. Click OK.